IEEE TRANSACTIONS ON ELECTRONICS PACKAGING MANUFACTURING, VOL. 33, NO. 4, OCTOBER 2010 289 Time–Frequency and Autoregressive Techniques for Prognostication of Shock-Impact Reliability of Implantable Biological Electronic Systems Pradeep Lall, Senior Member, IEEE, Prashant Gupta, Manish Kulkarni, and James Hofmeister Abstract—In this paper, autoregressive and time–frequency- based techniques have been investigated to predict and mon- itor the damage in implantable biological electronics such as pacemakers and defibrillators. The approach focuses is on the pre-failure space and methodologies for quantification of failure in electronic equipment subjected to shock and vibration loads using the dynamic response of the electronic equipment. Pre- sented methodologies are applicable at the system-level for iden- tification of impending failures to trigger repair or replacement significantly prior to failure. Leading indicators of shock-damage have been developed to correlate with the damage initiation and progression in under variety of stresses in electronic systems. The approach is based on monitoring critical solder interconnects, and sensing the change in test-signal characteristics prior to failure, in addition to monitoring the transient strain character- istics optically using digital image correlation and strain gages. Previously, SPR based on wavelet packet energy decomposition and the Mahalanobis distance approach have been studied by the authors for quantification of shock damage in electronic as- semblies (“Solder-joint reliability in electronics under shock and vibration using explicit finite element sub-modeling,” P. Lall, et al.Proc. 56th ECTC, May-Jun. 2006, pp. 428–435, “Life predic- tion and damage equivalency for shock survivability of electronic components,” P. Lall, et al. Proc. ITherm, May–Jun., 2006, pp. 804–816). In this paper, Autoregressive (AR), wavelet packet en- ergy decomposition, and time–frequency (TFA) techniques have been investigated for system identification, condition monitoring, and fault detection and diagnosis in implantable biological elec- tronic systems. One of the main advantages of the AR technique is that it is primarily a signal-based technique. Reduced re- liance on system analysis helps avoid errors which otherwise may render the process of fault detection and diagnosis quite complex and dependent on the skills of the analyst. Results of the present study show that the AR and TFA-based health monitoring tech- niques are feasible for fault detection and damage-assessment in electronic units. Explicit finite-element models have been devel- oped and various kinds of failure modes have been simulated such as solder ball cracking, package falloff, and solder ball failure. Index Terms—Biomedical electronics, integrated circuit inter- connections, integrated circuit reliability, mechanical shock and vi- bration, prognostics and health management, solder interconnects. Manuscript received December 28, 2008; revised June 11, 2009; accepted September 09, 2010. Date of publication October 04, 2010; date of current ver- sion November 24, 2010. The research presented in this paper was supported by the National Science Foundation under Grant ECCS-0740012. This work was recommended for publication by Associate Editor L. T. Nguyen upon evalua- tion of the reviewers comments. P. Lall, P. Gupta, and M. Kulkarni are with the Department of Mechanical Engineering, and NSF Center for Advanced Vehicle and Extreme Environment Electronics CAVE , Auburn University, Auburn, AL 36849 USA (e-mail: lall@auburn.edu; lall@eng.auburn.edu). J. Hofmeister is with the Ridgetop, Inc., Tucson, AZ 85704 USA. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TEPM.2010.2078824 I. INTRODUCTION I N THIS paper, an approach has been presented to address the ultra-high reliability needed in implantable biolog- ical electronic systems. Published studies based on FDA and non-FDA data have documented implanted pacemaker and ICD device failures, several thousands advisories, and an increasing rate of recall. In several cases device malfunctions have been investigated by explanting the device and have been linked to patient death. Dominant failure modes include capacitor, connector, and electrical anomalies. Since pacemakers and ICD are life-sustaining devices, there is need for methodologies for identification of impending failure significantly prior to catastrophic failure. Leading indicators of failure have the potential of substan- tially improving the implantable biological electronic system reliability by development of information on dominant failure mechanisms, leading-indicators of failure, and the models for determination of residual life. Implantable biological elec- tronics are finding applications in new types of therapies, by providing alternatives to medication in the form of medical systems. Examples include pacemakers for treating conduction disorders such as bradycardia; defibrillators to treat ventricular and atrial tachyarrhythmia and fibrillation. Pacemakers and implantable cardioverter-defibrillators (ICDs) are among the most critical life-support and complex medical devices in use today. However, several recent high-profile device malfunctions have called into question their safety and reliability. Several database registries including the United Kingdom, Danish, and Bilitch Registries have monitored pacemaker and ICD safety performance. In total, hundreds of device malfunctions affecting dozens of pacemaker and ICD models have been reported. A study of pacemaker and ICD advisories, a surrogate marker of device reliability, demonstrated that the number and rate of pacemakers and ICDs affected by advisory has increased since 1995. [18], [31], [32], [33], [45], [46]. Capacitor, connector, and electrical anomalies are among the most common cause of pacemaker and ICD malfunctions. Marked reduction and increased sophistication of devices are among the causes targeted for the observed increases in mal- function rate. In several cases, design evolution in device and packaging technology have led to unanticipated device failures [31], [32], [33], [34], [35], [46]. In a recent study, of U.S. Food and Drug Administration (FDA) data between the years of 1990 and 2002, there were 2.25 million pacemakers and almost 416 000 ICDs implanted in the U.S. [34], [35] During this same time period, 17 323 devices (8834 pacemakers and 1521-334X/$26.00 © 2010 IEEE